Field of the Invention
The present disclosure relates to an image forming apparatus, an image forming method, and a sheet-feeding apparatus. More particularly, the present disclosure relates to a sheet-feeding control for a copying machine, a printer, and the like, which are configured to perform image formation on a sheet.
Description of the Related Art
An electrophotographic image forming apparatus includes a sheet-feeding cassette and a sheet-feeding tray, e.g., a manual feed tray, and is configured to feed a sheet placed on the sheet-feeding cassette or the sheet-feeding tray to an image forming section for performing image formation. In particular, when image formation is performed on a thick sheet, a coated sheet, or another sheet having a large basis weight which cannot be handled by the sheet-feeding cassette, the manual feed tray is widely used.
In Japanese Patent Application Laid-open No. Hei 7-97079, there is disclosed a drive transmission mechanism including a pickup roller configured to feed a sheet placed on a manual feed tray and a sheet-feeding roller located downstream in a conveying direction. The pickup roller and the sheet-feeding roller are driven by the same drive power source. A support arm for the pickup roller is swung upward and downward each time the pickup roller performs sheet feeding, thereby allowing an uppermost sheet on the sheet-feeding tray to be fed to an image forming section one after another.
Further, hitherto, there has been a demand for an image forming apparatus to shorten a first copy time, which is a time period from pressing a copy key to outputting a first copy. As a matter of course, it is desired that the first copy time be shortened also in the case of sheet feeding from the manual feed tray described above.
There has been widely known a function called “fixed size mode” of setting in advance a size of a sheet to be used with the manual feed tray for the purpose of improving usability for a user who frequently uses the manual feed tray. Enabling this function can eliminate an annoying operation of performing size setting through an operation unit each time the manual feed tray is used.
However, in the related art, the pickup roller is raised each time one sheet is fed from the manual feed tray regardless of whether or not the fixed size mode is enabled. As a result, the pickup roller waits at an upper limit position, which is an initial position, when a sheet-feeding operation is not performed. When printing is started, sheet feeding is delayed by a time period of lowering the pickup roller from the upper limit position to a surface of a sheet on the manual feed tray for sheet feeding and a waiting time until vibration of the pickup roller on the sheet is ceased. This delay time may cause the first copy time to be lengthened.